Sliding motion

Lubrieation problems are a major eonsideration in the use of gear eouplings. Relative sliding between the teeth of the hub and the sleeve requires proper lubrieation to assure long eomponent life. This sliding motion is alternative and is eharaeterized by small amplitudes and relatively high frequeneies. 

FIGURE 10.37 Gap Juoctioos consist of hexameric arrays of cylindrical protein subunits in the plasma membrane. The subunit cylinders are tilted with respect to the axis running through the center of the gap Junction. A gap Junction between cells is formed when two hexameric arrays of subunits in separate cells contact each other and form a pore through which cellular contents may pass. Gap Junctions close by means of a twisting, sliding motion in which the subunits decrease their tilt with respect to the central axis. Closure of the gap Junction is Ca -dependent. 

FIGURE 17.7 A mechanism for ciliary motion. The sliding motion of dyneins along one microtnbnle while attached to an adjacent microtnbnle resnlts in a bending motion of the axoneme. 

The shortening of a sarcomere (Eigure 17.22) involves sliding motions in opposing directions at the two ends of a myosin thick filament. Net sliding motions in a specific direction occur because the thin and thick filaments both have... 

Static friction, which exists when sliding motion starts from rest ... 

The Ca -ATPase has been crystallized in both conformations [119,152-155]. The two crystal forms are quite different [10,88-93,156-161], suggesting significant differences between the interactions of Ca -ATPase in the Ei and E2 conformations. Since the Ei-E2-transition does not involve changes in the circular dichroism spectrum of the Ca -ATPase [162], the structural differences between the two states presumably arise by hinge-like or sliding motions of domains rather than by a rearrangement of the secondary structure of the protein. 

For the same experimental conditions as described in the flow experiments, (i.e., 10 pm glass particles, pure water flowing solution) centrifuge tests yield a higher force to release particles. The torque required for particle release is the same in both experiments hence, particle release in the flow cell is initiated by a rolling rather than sliding motion (Figure 9). 

Figure 17 Mechanical equilibrium position for adsorbed atoms between two commensurate solid surfaces as a function of relative displacement Axwan between the walls. The gray lines indicate the motion of the adsorbed atom if the walls are in slow relative sliding motion, (a) Vi < 0, (b) Vi = 0, and (c) Vi > 0. Reproduced with permission from Ref. 25.

Step 3 Determine the capsule size by using the rule of six. Capsule size 3 can hold 3 grains or 195 mg. Weigh 200 mg of the tablet mixture (which is obtained as 2000 mg of total powder/10 capsules) and try to fill in capsule size 3. If the capsule is not filled or it is too full, go for the next capsule size, i.e., 2 which holds approximately 4 grains or 260 mg of powder. Verify the appropriateness by filling one or two capsules of size 2. If appropriate, select this size. For 10 capsules, the total powder should be 2600 mg. Therefore add 600 mg of lactose in the tablet mixture of 2000 mg by geometric dilution. Transfer the 2600 mg of powder on a clean paper or an ointment tile, compress as a cake, and fill all the capsules by a sliding motion. 

In contrast to this, for a crystalline solid, the free movement of the adsorbed molecules is very much restricted by the periodic nature of the force fields at such surfaces. Then the activation energy to move from one place of adsorption to another (Alf ) becomes very important. Little is known, theoretically or experimentally, about the size of AH relative to AH, but it is generally considered H5-47) thafAH is about AH/2 or less. Movement of molecules along this surface takes place by a series of jumps from site to site rather than by a sliding motion. 

A related imidazole-appended zinc(II) porphyrin linked via an ethynylphenyl unit to a magnesium(II) phthalocyanine has recently been reported [38], The imidazole group binds to the magnesium center to form a stacked dimer in noncoordinating solvents such as chloroform even at submicromolar concentration (<10-6M). Upon addition of dimethyl sulfoxide, the stacked dimer transforms to an extended dimer in which the imidazole group binds to the zinc center on the basis of the hard and soft acid and base principle. The extended dimer exhibits a much stronger fluorescence (by a factor of 28) compared with the stacked dimer, and this coordination-induced sliding motion has been found to be reversible. 

Figure 6.3. Stractuie and function of myofilaments, a Arrangement of proteins within the filaments, b, c Mechanism of myofilament motion. Calcium binds to troponin, which in tnm causes tropomyosin to move and expose the myosin binding site on actin. Binding to actin canses the myosin heads to kink, which translates into a sliding motion, c The kinked conformation of myosin cleaves ATP. In the process, myosin releases itself from actin and letnms to the extended conformation it then binds to another actin monomer, and the cycle is repeated.

In the presence of a lubricating liquid (i.e., the polish slurry) two solid bodies in relative sliding motion will interact in one of... 

Each actin filament slides along adjacent myosin filaments with the help of other proteins and ions present in the cell. Tropomyosin and troponin are two proteins attached to the actin filaments that enable the globular heads on myosin to instantaneously attach to the myosin strands. The attachment and rapid release of this bond induces the sliding motion of these filaments which result in muscle contraction. In addition, calcium ions and ATP (cellular energy) are required by the muscle cell to process this reaction. Numerous mitochondria are present in muscle fibers to supply the extensive ATP required by the cell. 

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